Generator question for the old school guys

[TWChamp]

An alternator needs electricity to excite the windings, but once it's working you can disconnect the battery and the engine should keep running. This isn't a good idea to leave it unhooked from the battery, but we did it a lot at the junk yards to check for a good working alternator.

I restored a generator I bought from French Lake Auto Parts for my 1950 Champion, and now it charges at idle. With the rebuilt generator that the seller just installed in the car, the generator wouldn't start charging until the engine reached about 800 RPM.

It isn't a good idea to just switch wires to see what happens, as it could very well burn out the generator, regulator, and wires.
Once a battery is charged up, the ammeter should be just barely on the charge side of zero. If it stays on 5 to 10 amps, or even more, you will cook the water out of the battery and could also buckle the plates from overcharging.

[rstrasser]

If you remove the band on the generator you should see that the one terminal is connected to a brush holder. That is the armature terminal. The other terminal should be connected to a wire coming from one of the field coils. The field wire should also be a smaller gauge then the armature wire.
if the drawing that I have is correct (it is of an old Delco regulator) the armature wire goes to the center terminal. Most if not all Delco generators ground the field terminal through the regulator. With the engine running disconnection the field wire on the generator and connecting it to ground for a few seconds should cause the generator to go to full output.
Ron

[nebraska stude]

Old mechanic here. Tying the two battery cables together would do nothing but fry the generator once the engine started, which I doubt it would with the + grounded. Was told in school that a car with alternator would shut down if the battery cable is unhooked. Surprise, if the car has a lot of miles on it, there is induced magnetism in the alternator and the car stays running. To get two of them to shut down, had to disconnect the big wire from the alternator, with it running, one does this very carefully.

[rusty_apache]

You may have corrected the polarity, but your regulator may eventually may fail if you don't polarize the system.
I run generators when originally equipped and they all run with the battery disconnected when working properly.
Diodes will fry if you try the battery trick with an alternator setup. Especially if you rev the engine high.

[Okiejoe86]

In your two photos, the regulator wires appear correct. At the generator I think I can actually see a letter 'A' stamped into the case at the upper terminal. That terminal should hold the white wire.

Charging rate as shown on the ammeter is inversely proportional to battery state of charge.

The "A" that you see must be a dent or rust under the paint. I have looked and am unable to see any letters stamped on it.

Thanks for your input!

[Dwain G.]

In your two photos, the regulator wires appear correct. At the generator I think I can actually see a letter 'A' stamped into the case at the upper terminal. That terminal should hold the white wire.

Charging rate as shown on the ammeter is inversely proportional to battery state of charge.

[Okiejoe86]

I love this forum! Thank You Everyone for the input!!

[52-fan]

RE The engine running without a battery. My former brother-in-law and some high school friends bought an old military jeep to go into the hills, but they could not afford a battery. He told me they just tied the battery cables together and always parked on a hill so they could roll start the jeep.

[41 Frank]

Sounds like you fixed it!

[Okiejoe86]

The most likely result of reversing field and armature wires is destruction of the regulator.
The generator is disconnected from the battery via the cutout relay in the regulator. This may occur at idling.
The ammeter may read consistently high if an electrical load is not wired through the ammeter. A bad cell in the battery may also require a greater current.
A bouncy ammeter is an indication the regulator is not perfect. It may continue to function for a long time though.
Most of the electrical problems on the forum turn out to be poor or misplaced connections. You mention that you just rewired the vehicle?

I did just rewire the car. I swapped the two wires on the generator just to see what happened. Now my ammeter is reading up to 30amps. Not sure if this is a good indication or bad.

[greyben]

The most likely result of reversing field and armature wires is destruction of the regulator.
The generator is disconnected from the battery via the cutout relay in the regulator. This may occur at idling.
The ammeter may read consistently high if an electrical load is not wired through the ammeter. A bad cell in the battery may also require a greater current.
A bouncy ammeter is an indication the regulator is not perfect. It may continue to function for a long time though.
Most of the electrical problems on the forum turn out to be poor or misplaced connections. You mention that you just rewired the vehicle?

[rstrasser]

The picture that I have of a Delco regulator shows the terminals as follows. Left most terminal goes to the battery. The center terminal that is right of center goes to the Armature terminal of the generator and the right most terminal goes to the field terminal on the generator. I am unable to make out any marking on the generator as to which is the field or armature terminal. Nor do I know what would happen if you reversed the field and armature terminals. Never tried it. If anyone has, let us all know what happens then we can all learn.
Ron

[Okiejoe86]

Ammeters don't care which way the current goes. If you wire it up backwards, it will just show discharge when it the generator is charging.

Thanks for the input!

[Skip Lackie]

It is possible that I may have a few wires swapped at the generator and regulator. Here is a picture of my connections.

Also, Is is possible to wire the ammeter gauge backwards and it will read backwards or not read at all??

Thankyou for the input everyone!

[ATTACH=CONFIG]53046[/ATTACH][ATTACH=CONFIG]53047[/ATTACH]

Ammeters don't care which way the current goes. If you wire it up backwards, it will just show discharge when it the generator is charging.

[Okiejoe86]

YEAH! I have hit a milestone and hit 100 posts!!!!!! ..random note